Outflow channels

Crater counts indicate that most of the channels were cut since the early Hesperian,[2] though the age of the features is variable between different regions of Mars.

Some outflow channels in the Amazonis and Elysium Planitiae regions have yielded ages of only tens of millions of years, extremely young by the standards of Martian topographic features.

[9][10] Calculations[11][12] indicate that the volumes of water required to cut such channels at least equal and most likely exceed by several orders of magnitude the present discharges of the largest terrestrial rivers, and are probably comparable to the largest floods known to have ever occurred on Earth (e.g., those that cut the Channeled Scablands in North America or those released during the re-flooding of the Mediterranean basin at the end of the Messinian Salinity Crisis).

[3] Several outflow channels rise in the region west of the Elysium volcanic province and flow northwestward to the Utopia Planitia.

It has been argued that Uzboi, Ladon, Margaritifer and Ares Valles, although now separated by large craters, once comprised a single outflow channel flowing north into Chryse Planitia.

[15] The source of this outflow has been suggested as overflow from the Argyre crater, formerly filled to the brim as a lake by channels (Surius, Dzigai, and Palacopus Valles) draining down from the south pole.